what did the nine hens die of

They die of starvation.

they died of coccidiosis

They were executed!

"The three hens who had been the ringleaders in the attempted rebellion

over the eggs now came forward and stated that Snowball had appeared to

them in a dream and incited them to disobey Napoleon's orders. They, too,

were slaughtered."

Sorry to everyone, Aslans right, I didn't see the "9" there. Yes, Napoleon was busy starving them into submission. Apologies!